12 research outputs found
Observation of generalized optomechanical coupling and cooling on cavity resonance
Optomechanical coupling between a light field and the motion of a cavity
mirror via radiation pressure plays an important role for the exploration of
macroscopic quantum physics and for the detection of gravitational waves (GWs).
It has been used to cool mechanical oscillators into their quantum ground
states and has been considered to boost the sensitivity of GW detectors, e.g.
via the optical spring effect. Here, we present the experimental
characterization of generalized, that is, dispersive and dissipative
optomechanical coupling, with a macroscopic (1.5mm)^2-sized silicon nitride
(SiN) membrane in a cavity-enhanced Michelson-type interferometer. We report
for the first time strong optomechanical cooling based on dissipative coupling,
even on cavity resonance, in excellent agreement with theory. Our result will
allow for new experimental regimes in macroscopic quantum physics and GW
detection
Tomographic readout of an opto-mechanical interferometer
The quantum state of light changes its nature when being reflected off a
mechanical oscillator due to the latter's susceptibility to radiation pressure.
As a result, a coherent state can transform into a squeezed state and can get
entangled with the motion of the oscillator. The complete tomographic
reconstruction of the state of light requires the ability to readout arbitrary
quadratures. Here we demonstrate such a readout by applying a balanced homodyne
detector to an interferometric position measurement of a thermally excited
high-Q silicon nitride membrane in a Michelson-Sagnac interferometer. A readout
noise of \unit{1.9 \cdot 10^{-16}}{\metre/\sqrt{\hertz}} around the
membrane's fundamental oscillation mode at \unit{133}{\kilo\hertz} has been
achieved, going below the peak value of the standard quantum limit by a factor
of 8.2 (9 dB). The readout noise was entirely dominated by shot noise in a
rather broad frequency range around the mechanical resonance.Comment: 7 pages, 5 figure
Engineered entropic forces allow ultrastrong dynamical backaction
When confined within an optical cavity, light can exert strong radiation
pressure forces. Combined with dynamical backaction, this enables important
processes such as laser cooling, and applications ranging from precision
sensors to quantum memories and interfaces. However, the magnitude of radiation
pressure forces is constrained by the energy mismatch between photons and
phonons. Here, we overcome this barrier using entropic forces arising from the
absorption of light. We show that entropic forces can exceed the radiation
pressure force by eight orders of magnitude, and demonstrate this using a
superfluid helium third-sound resonator. We develop a framework to engineer the
dynamical backaction from entropic forces, applying it to achieve phonon lasing
with a threshold three orders of magnitude lower than previous work. Our
results present a pathway to exploit entropic forces in quantum devices, and to
study nonlinear fluid phenomena such as turbulence and solitons.Comment: Main text is 10 pages, 5 figures. Supplements is 21 pages, 11 figure
Phonon confinement by the force of light
Using superfluid optomechanical system, here we show both that radiation pressure can greatly deform superfluid film, increasing its local thickness by over a factor of 2, and that this generates new sound modes within the film locally, that are confined by the optical mode and interact strongly with it. This demonstrates a new form of dynamical backaction between the intensity of light within a cavity and the shape of the mechanical eigenmodes that it creates
Strong optical coupling through superfluid Brillouin lasing
Brillouin scattering has applications ranging from signal processing, sensing and microscopy to quantum information and fundamental science. Most of these applications rely on the electrostrictive interaction between light and phonons. Here we show that in liquids optically induced surface deformations can provide an alternative and far stronger interaction. This allows the demonstration of ultralow-threshold Brillouin lasing and strong phonon-mediated optical coupling. This form of strong coupling is a key capability for Brillouin-reconfigurable optical switches and circuits, for photonic quantum interfaces and to generate synthetic electromagnetic fields. While applicable to liquids quite generally, our demonstration uses superfluid helium. Configured as a Brillouin gyroscope this provides the prospect of measuring superfluid circulation with unprecedented precision, and exploring the rich physics of quantum fluid dynamics, from quantized vorticity to quantum turbulence
Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO
International audienceDuring their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100ââMâ, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93ââGpcâ3âyrâ1 in comoving units at the 90%Â confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits